1. Field of the Invention
The invention relates to a computer system, and more particularly to a computer system capable of detecting a Universal Serial Bus (USB) device.
2. Description of the Related Art
Currently, a basic input/output system (BIOS) code used to perform boot processes by most computer systems is stored in a read only memory (ROM) of the computer system, such as a serial peripheral interface (SPI) flash memory. When the computer system is enabled, a central processor (CPU) will perform a power-on self test (POST) procedure according to the BIOS code, to check whether each of the basic equipment (e.g. motherboard, graphics card) is normal, and then subsequent procedures are performed. The BIOS code is used to manage the configuration of system date, display mode, floppy disk drives, hard disk type, peripherals (e.g. communication ports, printing port, etc.), and random access memory (RAM) and cache memory. Therefore, the BIOS code is an important boot program for the computer system.
Because Universal Serial Bus (USB) devices are in compliance with Plug and Play, providing universality and convenience of the devices, they have long been widely used in computer peripheral devices. Common computer peripherals, such as mouse, keyboard, storage devices, and so on, all use the USB interface. In the Windows operating system (OS), system authentication defines at least one USB port needing to be equipped, and the boot and debug procedures can be performed via the USB port. Therefore, a device functioning as a boot disk via the USB port is important for the computer system.
For portable computer products, system boot time is usually an important indicator of a system's performance. Windows8/Windows8.1 system authentication has a definite specification for the system boot time. For example, when the storage device is a solid-state drive (SSD) or a hybrid SSD, the computer system needs to complete the boot process within 2 seconds. When the storage device is a traditional motor-driven rotating hard disk, the computer system needs to complete the boot process within 4 seconds.
As manufacturers of USB devices are numerous and initialization time is different for each USB device, when the computer system is ready to determine whether a USB device is inserted/plugged in, if the USB device does not complete its initialization, it will cause the computer system to mistakenly determine that no USB device is plugged in. Therefore, a computer system capable of detecting a USB device is desired.